CN112152048A - Few-period high-field-intensity coherent THz radiation source generation system - Google Patents

Few-period high-field-intensity coherent THz radiation source generation system Download PDF

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Publication number
CN112152048A
CN112152048A CN202010947318.6A CN202010947318A CN112152048A CN 112152048 A CN112152048 A CN 112152048A CN 202010947318 A CN202010947318 A CN 202010947318A CN 112152048 A CN112152048 A CN 112152048A
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parabolic mirror
axis parabolic
radiation source
few
thz radiation
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王剑
余同普
刘德会
罗嘉琪
曾澝菡
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Neijiang Normal University
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Neijiang Normal University
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01SDEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S1/00Masers, i.e. devices using stimulated emission of electromagnetic radiation in the microwave range
    • H01S1/06Gaseous, i.e. beam masers

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  • Engineering & Computer Science (AREA)
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Abstract

The invention discloses a few-period high-field-intensity coherent THz radiation source generation system, which comprises an ultra-short pulse laser (100) and a vacuum target chamber system (101), wherein an ultrasonic nozzle system (102), a short-focus off-axis parabolic mirror (103), an off-axis parabolic mirror (104) and a light path system are arranged in the vacuum target chamber system (101), the ultra-short pulse laser (100) is connected with the short-focus off-axis parabolic mirror (103), the short-focus off-axis parabolic mirror (103) is connected with the ultrasonic nozzle system (102), the ultrasonic nozzle system (102) is connected with the off-axis parabolic mirror (104), and the off-axis parabolic mirror (104) is connected with the light path system; a high power THz radiation source is generated based on the interaction of femtosecond laser pulses with a supersonic jet target or gas chamber.

Description

Few-period high-field-intensity coherent THz radiation source generation system
Technical Field
The invention relates to the technical field of terahertz light sources, in particular to a few-period high-field-intensity coherent THz radiation source generation system.
Background
Terahertz (T-ray) light sources are considered as next-generation light sources, and applications range from cancer diagnosis to material science. Due to its non-ionizing properties, good spatial resolution andthe ability to penetrate biological tissue several millimeters. In the context of cancer detection, T-rays are a suitable alternative to X-rays. In addition to biological imaging, powerful T-rays have many applications in material science as diagnostic tools, such as ultrafast spectroscopy. By focusing the high power T-ray to a millimeter spot size, an electric field on the order of GV/m can be generated. The electric field can be used to study the structural transformation of polar molecules. The associated tesla transient magnetic field can be used to generate magnetic or spin excitation and track its dynamics on a picosecond time scale. Currently available high-power T-ray sources are produced from large facilities such as linear accelerators to compact light sources based on electro-optic crystals. In the linear accelerator, relativistic electrons are converged by a bending magnet to generate a terahertz light beam with the peak power of MW. Electro-optic crystal based light sources use high repetition rate laser systems to generate T-rays by optical rectification in a nonlinear crystal. Both sources have both advantages and disadvantages. For example, accelerator-based T-ray sources are high peak power MW, high repetition rate sources, however, they are bulky, expensive and therefore offer only fairly limited availability. Based on optical rectification or more economical compact light sources, T-ray pulses comparable to the accelerator light source energy can be achieved, however, the damage threshold of the nonlinear crystal limits the T-ray field strength. The plasma does not have such a limitation. Therefore, the laser plasma THz light source has been a hot topic of research. In fact, the mechanisms by which T-rays are generated are diverse. For a plasma filament generated by bicolor laser, the energy of T rays is up to 5 mu J, and the conversion efficiency is 10-4. However, at higher laser intensities, terahertz radiation tends to saturate due to intensity clamping, low electron density, and reabsorption of the radiation. The plasma generated during the interaction of high power lasers with solids is not so limited and is also a known high field strength T-ray source, but is less well studied.
Prior art [1 ]: proof of principle tests by Yugami et al, university of Yudou, Japan, demonstrated that in a perpendicular magnetized plasma, an ultrashort, ultrahigh power pulsed laser excites the Cerenkov wake to generate radiation (see the article https:// doi. org/10.1103/PhysRevLett.89.065003). The radiation frequency is in the millimeter range (up to 200 gigahertz). The radiation intensity is proportional to the theoretically expected magnetic field strength. The polarization of the emitted radiation is also detected.
Prior art [2 ]: yi et al, charlemerss theory of physical engineering, switzerland, proposed a method for generating high-intensity terahertz (THz) pulses by irradiating a plasma waveguide with high-power laser light. When a laser pulse enters the plasmonic waveguide, a highly charged electron beam is generated and accelerated to 100 MeV by the transverse electromagnetic mode. When the electron beam leaves the plasmonic waveguide, a significant portion of the electron energy is transferred to the THz radiation by coherent diffracted radiation. The result shows that 100 mJ-level relativistic strong terahertz pulses with adjustable frequency can be generated on the existing laser device.
Prior art [3 ]: d' Amico, national institute of technology, France, discovered that THz radiation (see the article https:// doi. org/10.1103/PhysRevLett.98.235002), generated in air, was emitted forward in the form of a strongly collimated terahertz beam, which they attributed to the transition in the wake field of Cherenkov radiation, generated by space charges moving at the speed of light generated after the ionization front. It uses normal air as generating medium, only needs one femtosecond laser beam, and does not need precise alignment. More importantly, the terahertz radiation source can be easily positioned in a place very close to the target, possibly several kilometers away, so that the problem of transmission of terahertz radiation in the air is solved. This new terahertz radiation amplitude exceeds other radiation sources by orders of magnitude in terms of effective radiation to distant targets.
Prior art [4]: the grand and well-known topic team of Shanghai traffic university found that strong low frequency radiation (https:// doi. org/10.1103/PhysRevE.69.025401) with a center frequency near the reciprocal of the drive pulse duration was observed at the vacuum-plasma interface. The radiation originates from large amplitude plasma waves excited at the plasma boundary. For 3X 1017 W/cm2The induced radiation power of the incident pulse can reach megawatt level, and the energy is millijoule level. It has been found that an appropriate density scale length near the plasma boundary is advantageous for generating induced emission. Such density distributionThis can be achieved by emitting laser pulses laterally into the gas jet or, when a solid target is used, by adjusting the delay of the pre-pulse from the main pulse.
In order to generate THz with high field strength more efficiently and to realize practical application of light sources in related scientific fields, researchers have proposed various methods to improve the field strength and energy conversion efficiency of THz sources. However, in the prior art, besides the low conversion efficiency, the alignment of the laser is difficult, and a new technical solution is needed.
Disclosure of Invention
The invention aims to design a few-period high-field-intensity coherent THz radiation source generating system, which generates a high-power THz radiation source based on the interaction of femtosecond laser pulses and an ultrasonic air jet target or an air chamber.
The invention is realized by the following technical scheme: the utility model provides a few periods high field intensity coherent THz radiation source generating system, includes ultrashort pulse laser and vacuum target chamber system, be provided with supersonic nozzle system, short focus off-axis parabolic mirror, off-axis parabolic mirror and light path system in the vacuum target chamber system, ultrashort pulse laser connects short focus off-axis parabolic mirror, and short focus off-axis parabolic mirror connects supersonic nozzle system, and supersonic nozzle system connects off-axis parabolic mirror, and light path system is connected to off-axis parabolic mirror.
In order to further realize the invention, the following arrangement mode is adopted: the optical path system comprises a spectrum beam splitter, a band-pass filter, a polarizer and a pyroelectric THz detector, and the off-axis parabolic mirror is sequentially connected with the spectrum beam splitter, the band-pass filter, the polarizer and the pyroelectric THz detector.
In order to further realize the invention, the following arrangement mode is adopted: in the vacuum target chamber system, a spectrum spectroscope, a band-pass filter, a polarizer and a pyroelectric THz detector are arranged on the same optical axis.
The short-focus off-axis parabolic mirror, the off-axis parabolic mirror with the through hole, the spectrum beam splitter, the band-pass filter, the polarizer and the pyroelectric THz detector are sequentially placed in the vacuum target chamber and are coaxial and equal in height.
In order to further realize the invention, the following arrangement mode is adopted: the ultrashort pulse laser adopts a mesa ultrashort pulse laser with the pulse width less than 30 femtoseconds and the single-shot energy less than 1 joule.
In order to further realize the invention, the following arrangement mode is adopted: the supersonic nozzle system is arranged in the center of a target chamber of the vacuum target chamber system, and the height of the center of an air column sprayed out by the supersonic nozzle system is the same as that of the center of the short-focus off-axis parabolic mirror.
In order to further realize the invention, the following arrangement mode is adopted: the supersonic nozzle system adopts a Japanese SMARTSHELL supersonic gas nozzle system, and the main structure of the supersonic nozzle system is a controller, an electromagnetic valve and a supersonic nozzle.
In order to further realize the invention, the following arrangement mode is adopted: the short-focus off-axis parabolic mirror adopts a short-focus off-axis parabolic mirror with a relative aperture of F/3.
In order to further realize the invention, the following arrangement mode is adopted: the off-axis parabolic mirror is an off-axis parabolic mirror with a through hole, the diameter of the through hole is 3 mm, the off-axis angle is 50.8 mm, the reflection focal length is 101.6 mm, and the bus focal length is 50.8 mm.
In order to further realize the invention, the following arrangement mode is adopted: the length of the laser pulse generated by the ultrashort pulse laser is far less than the plasma wavelength formed after the gas filled in the supersonic nozzle of the supersonic nozzle system is ionized.
Compared with the prior art, the invention has the following advantages and beneficial effects:
the invention overcomes the limitation of the prior scheme of generating the high-field THz source, and adopts the interaction of the tightly focused femtosecond laser and the rarefied helium. When laser is transmitted in the thin plasma, displacement current which changes along with time is formed through a cavitation bubble tail field generated by the laser, and then a self-generated angular magnetic field is generated. Under the action of the self-generated angular magnetic field, electromagnetic waves are radiated through a Cerenkov radiation mechanism, and the frequency of the electromagnetic waves is slightly higher than that of plasma. When the gas density is constant, the radiated electromagnetic wave is THz wave.
The invention can adopt the interaction mode of femtosecond laser with extremely short pulse width and supersonic jet to obtain the THz ray source with extremely high field intensity, and the THz ray source can be used as a high-performance THz ray source for detection and diagnosis in the fields of security, biomedicine and the like.
The invention has the characteristics of high field strength (Kyoto V/m), short time scale (subpicosecond), higher conversion rate (0.1%), and small space divergence angle (hundred milliradian level), is suitable for the detection neighborhood of THz rays with high space-time resolution, is also suitable for the field of biomedical imaging, and is possibly suitable for the field of material control.
The invention has the characteristic of high field intensity, and the electric field intensity of the radiated THz wave is dozens of GV/m by adopting the magnetized Cerenkov tail field, which is far higher than the THz source which is mainstream at present. The field strength is comparable to that of prior art [2], and according to literature investigations, is the strongest THz electric field known at present.
The invention has the characteristic of broad spectrum, and the generation medium of the THz wave is plasma. Thus, in essence, the THz wave must be broad-spectrum, with a frequency broadening of up to 100% and a center frequency near the plasma wavelength, slightly above the plasma eigenfrequency.
The THz radiation source has the characteristic of high time resolution, and because the working medium of the THz radiation source is nonlinear plasma wave and only has 1-2 oscillation periods, the THz radiation source only has 1-2 plasma periods, and finally the total pulse width is less than 1 picosecond, and the THz radiation source has the characteristic of high time resolution.
The invention has controllable cost, and the related technology is completely feasible after being verified by a high-power laser device. The mature commercial repetition frequency Taiwa level laser at present can completely meet the requirement, does not need expensive additional equipment such as a super strong external magnetic field generating device, greatly improves the THz radiation field intensity, and simultaneously reduces the equipment purchase and maintenance cost as much as possible.
Compared with the prior art [2], the THz pulse generator can generate THz pulse by only one laser beam, does not need a complex and precise alignment technology, and greatly reduces the experimental difficulty. At the same time, no expensive and inefficient pre-pulse suppression measures need to be taken, compared to the prior art [3 ].
Drawings
FIG. 1 is a schematic view of the structure of the present invention.
The system comprises a 100-ultrashort pulse laser, a 101-vacuum target chamber system, a 102-supersonic nozzle system, a 103-short focal length off-axis parabolic mirror, a 104-off-axis parabolic mirror, a 105-spectral beam splitter, a 106-band-pass filter, a 107-polarizer and a 108-pyroelectric THz detector.
Detailed Description
The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.
In the description of the present invention, it is to be understood that the terms etc. indicate orientations or positional relationships based on those shown in the drawings only for the convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
It is worth noting that: in the present application, when it is necessary to apply the known technology or the conventional technology in the field, the applicant may have the case that the known technology or/and the conventional technology is not specifically described in the text, but the technical means is not specifically disclosed in the text, and the present application is considered to be not in compliance with the twenty-sixth clause of the patent law.
Example 1:
as shown in fig. 1, a few-period high-field-strength coherent THz radiation source generating system includes an ultrashort pulse laser 100 and a vacuum target chamber system 101, and is characterized in that: an ultrasonic nozzle system 102, a short-focus off-axis parabolic mirror 103, an off-axis parabolic mirror 104 and a light path system are arranged in the vacuum target chamber system 101, the ultra-short pulse laser 100 is connected with the short-focus off-axis parabolic mirror 103, the short-focus off-axis parabolic mirror 103 is connected with the ultrasonic nozzle system 102, the ultrasonic nozzle system 102 is connected with the off-axis parabolic mirror 104, and the off-axis parabolic mirror 104 is connected with the light path system.
As a preferred arrangement scheme, the few-period high-field-intensity coherent THz radiation source generating system is provided with an ultrashort pulse laser 100 for generating laser and a vacuum target chamber system 101 for converting laser waves into THz radiation sources, wherein the vacuum target chamber system 101 comprises an ultrasonic nozzle system 102, a short-focus off-axis parabolic mirror 103, an off-axis parabolic mirror 104 and a light path system; the light path of the ultra-short pulse laser 100 is connected with the short-focus off-axis parabolic mirror 103, and the short-focus off-axis parabolic mirror 103 focuses laser and projects the focused laser onto the plasma edge formed by the supersonic nozzle of the supersonic nozzle system 102.
During specific use, ultrashort laser pulses with pulse widths of only a plurality of laser periods are generated on a commercial laser device (ultrashort pulse laser 100), and are focused on the plasma edge formed by an ultrasonic nozzle of an ultrasonic nozzle system 102 through a short-focus off-axis parabolic mirror 103 with a relative aperture F/3, and the laser pulses push away electrons from the transverse direction and the radial direction to form nonlinear plasma waves. Because the ion background is kept still, under a certain density condition, a vacuole structure is formed in the plasma, and no loaded electron beam exists in the vacuole. The pushed away electrons flow back, thereby generating an angular magnetic field of a large scale, with a strength of tens of tesla. Under the action of the angular magnetic field, the plasma oscillation is changed from a pure electrostatic type to a partial electromagnetic type. Finally, the electromagnetic radiation is released at a frequency close to the plasma oscillation, and THz radiation waves with extremely high field intensity are formed. In order to separate the laser light passing through supersonic nozzle system 102, an off-axis parabolic mirror (preferably an off-axis parabolic mirror with a through hole) 104 is disposed on the light path, the main laser divergence angle is small, the THz radiation wave with a large divergence angle passes through the through hole, and the THz radiation wave with a large divergence angle is collected by off-axis parabolic mirror 104 with a through hole. In addition, an optical path system is provided on the optical path for further separation and detection.
Example 2:
the present embodiment is further optimized based on the above embodiment, and will not be described herein again in comparison with the foregoing technical solution and the foregoing technical solution, as shown in fig. 1, in order to further implement the present invention better, the following setting manner is particularly adopted: the supersonic nozzle system 102 is placed in the center of the target chamber of the vacuum target chamber system 101, and the height of the center of the air column sprayed out by the supersonic nozzle system 102 is the same as the height of the center of the short-focus off-axis parabolic mirror 103. The ultrashort pulse laser 100 is a mesa ultrashort pulse laser with a pulse width less than 30 femtoseconds and a single-shot energy less than 1 joule.
As a preferable arrangement, the ultrashort pulse laser 100 is a mesa ultrashort pulse laser with a center wavelength of 0.8 μm, a peak power of several tewatts, a repetition frequency of 10 hz, a pulse width of less than 30 femtoseconds, and a single-shot energy of less than 1 joule.
Example 3:
the present embodiment is further optimized based on any of the above embodiments, and its idea methods with the above technical solutions and the above technical solutions will not be described herein again, as shown in fig. 1, in order to further better implement the present invention, the following setting modes are particularly adopted: the optical path system comprises a spectrum splitter 105, a band-pass filter 106, a polarizer 107 and a pyroelectric THz detector 108, and the off-axis parabolic mirror 104 is sequentially connected with the spectrum splitter 105, the band-pass filter 106, the polarizer 107 and the pyroelectric THz detector 108.
In order to control the output spectral bandwidth, a band-pass filter 106 is disposed behind the spectral splitter 105, and the preferred band-pass filter can be configured with different bandwidths as required, and different bandwidths can be selected by using different band-pass filters. After the band-pass filter 106 a polarizer 107 is placed. By means of the polarizer 107, the polarization direction of the THz wave can be selected. Finally, the filtered and polarization-selected THz wave is detected by pyroelectric THz detector 108.
Example 4:
the present embodiment is further optimized based on any of the above embodiments, and its idea methods with the above technical solutions and the above technical solutions will not be described herein again, as shown in fig. 1, in order to further better implement the present invention, the following setting modes are particularly adopted: the supersonic nozzle system adopts a Japanese SMARTSHELL supersonic gas nozzle system, and the main structure of the supersonic nozzle system is a controller, an electromagnetic valve and a supersonic nozzle.
Example 5:
the present embodiment is further optimized based on any of the above embodiments, and its idea methods with the above technical solutions and the above technical solutions will not be described herein again, as shown in fig. 1, in order to further better implement the present invention, the following setting modes are particularly adopted: the short-focus off-axis parabolic mirror 103 adopts a short-focus off-axis parabolic mirror with a relative aperture of F/3.
Example 6:
the present embodiment is further optimized based on any of the above embodiments, and its idea methods with the above technical solutions and the above technical solutions will not be described herein again, as shown in fig. 1, in order to further better implement the present invention, the following setting modes are particularly adopted: the length of the laser pulse generated by the ultrashort pulse laser 100 is far shorter than the wavelength of the plasma formed after the gas filled in the supersonic nozzle of the supersonic nozzle system 102 is ionized.
Example 7:
the present embodiment is further optimized based on any of the above embodiments, and its idea methods with the above technical solutions and the above technical solutions will not be described herein again, as shown in fig. 1, in order to further better implement the present invention, the following setting modes are particularly adopted: the off-axis parabolic mirror 104 is an off-axis parabolic mirror with a through hole, and the through hole has a diameter of 3 mm, an off-axis angle of 50.8 mm, a reflection focal length of 101.6 mm, and a bus focal length of 50.8 mm.
Example 8:
as shown in FIG. 1, a few-cycle high-field coherent THz radiation source generation system comprises
The laser is designed by adopting an optical parameter chirped pulse amplification technology, the central wavelength is 0.8 micron, the peak power is several terawatts, the repetition frequency is 10 Hz, the pulse width is less than 30 femtoseconds, and the single-shot energy is less than 1 joule mesa type ultrashort pulse laser (ultrashort pulse laser 100);
and the vacuum target chamber system 101 is used for packaging the supersonic nozzle system 102, the short-focus off-axis parabolic mirror 103, the off-axis parabolic mirror 104, the spectral beam splitter 105, the band-pass filter 106, the polarizer 107 and the pyroelectric THz detector 108.
Wherein, supersonic nozzle system 102 is arranged behind short-focus off-axis parabolic mirror 103, and adopts supersonic nozzle system (its main structure is controller, electromagnetic valve and supersonic nozzle) of Japanese SMARTSHELL supersonic gas nozzle system;
a short focal length off-axis parabolic mirror 103 which is arranged behind the ultra-short pulse laser 100 and adopts a short focal length off-axis parabolic mirror with a relative aperture of F/3;
the off-axis parabolic mirror 104 is an off-axis parabolic mirror with a through hole, and is arranged behind the supersonic nozzle of the supersonic nozzle system 102 for realizing laser separation;
a spectral splitter 105 placed behind the off-axis parabolic mirror 104 for splitting the THz radiation;
a band-pass filter 106 disposed after the spectral splitter 105 for controlling the output spectral bandwidth;
a polarizer 107 disposed after the band pass filter 106 for selecting a polarization direction;
the pyroelectric THz detector 108 is arranged behind the polarizer 107, detects THz radiation waves by using the pyroelectric effect of electromagnetic waves, and can be assembled or disassembled as required by adopting a detachable arrangement mode.
In application, the ultrashort pulse laser 100 emits a spatio-temporal double-gauss ultrashort intense laser pulse. The length of the time-space double-Gaussian ultrashort strong laser pulse is less than 30 femtoseconds, and the energy is 0.1 joule. Focused to the supersonic nozzle edge of the supersonic nozzle system 103 through the short-focus off-axis parabolic mirror 103, so that the laser beam waist size is 13 microns, and the corresponding peak laser power density is 1.37 multiplied by 1018W/cm2. The polarization direction of the laser light is S polarization. Adjusting the back pressure of the supersonic nozzle to make the plasma density after laser pre-pulse ionization 1X 1018/cm3Corresponding to a plasma wavelength of 33And (3) micron. From a number of numerical calculations, it was found that a double-vacuole structure is created inside the plasma, which vacuole can be approximately seen as a sphere with a radius slightly larger than the beam waist of the driving laser. Meanwhile, electrons discharged by the laser flow back under the action of electrostatic force, and an angular magnetic field is formed. The magnitude of the magnetic field is 30T. At this time, the non-magnetized plasma becomes a locally magnetized plasma. However, since the magnetic field is not so strong, the plasma is in a weakly magnetized plasma state. Under the action of the azimuthal magnetic field, the plasma wave changes from a pure electrostatic mode to a partial electromagnetic mode. Therefore, THz radiation with field strength greater than 20 GV/m can be generated, the radiation frequency has a broad spectrum characteristic, and the center frequency is 15 THz. Such strong THz waves are very suitable for excitation and manipulation of polarized material molecules.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are within the scope of the present invention.

Claims (9)

1. A few-period high-field-strength coherent THz radiation source generation system comprises an ultrashort pulse laser (100) and a vacuum target chamber system (101), and is characterized in that: be provided with supersonic nozzle system (102), short focal length off-axis parabolic mirror (103), off-axis parabolic mirror (104) and light path system in vacuum target chamber system (101), short focal length off-axis parabolic mirror (103) is connected to ultrashort pulse laser (100), and supersonic nozzle system (102) is connected to short focal length off-axis parabolic mirror (103), and supersonic nozzle system (102) is connected off-axis parabolic mirror (104), and light path system is connected to off-axis parabolic mirror (104).
2. The few-cycle high-field coherent THz radiation source generating system of claim 1, wherein: the supersonic nozzle system (102) is placed in the center of a target chamber of the vacuum target chamber system (101), and the height of the center of an air column sprayed out by the supersonic nozzle system (102) is the same as that of the center of the short-focus off-axis parabolic mirror (103).
3. The few-cycle high-field coherent THz radiation source generating system of claim 1, wherein: the ultrashort pulse laser (100) adopts a mesa ultrashort pulse laser with the pulse width less than 30 femtoseconds and the single-shot energy less than 1 joule.
4. The few-cycle high-field coherent THz radiation source generating system of claim 1, wherein: the supersonic nozzle system (102) employs an SMARTSHELL supersonic gas nozzle system.
5. The few-cycle high-field coherent THz radiation source generating system of claim 1, wherein: the short-focus off-axis parabolic mirror (103) adopts a short-focus off-axis parabolic mirror with a relative aperture of F/3.
6. The few-cycle high-field coherent THz radiation source generating system of claim 1, wherein: the length of the laser pulse generated by the ultrashort pulse laser (100) is far less than the plasma wavelength formed after the gas filled in the supersonic nozzle of the supersonic nozzle system (102) is ionized.
7. The few-cycle high-field-strength coherent THz radiation source generating system of any one of claims 1 to 6, wherein: the optical path system comprises a spectrum light splitter (105), a band-pass filter (106), a polarizer (107) and a pyroelectric THz detector (108), and the off-axis parabolic mirror (104) is sequentially connected with the spectrum light splitter (105), the band-pass filter (106), the polarizer (107) and the pyroelectric THz detector (108).
8. The few-cycle high-field coherent THz radiation source generating system of claim 7, wherein: in the vacuum target chamber system (101), a spectrum spectroscope (105), a band-pass filter (106), a polarizer (107) and a pyroelectric THz detector (108) are arranged on the same optical axis.
9. The few-cycle high-field coherent THz radiation source generating system of claim 7, wherein: the off-axis parabolic mirror (104) is an off-axis parabolic mirror with a through hole, the diameter of the through hole is 3 mm, the off-axis angle is 50.8 mm, the reflection focal length is 101.6 mm, and the bus focal length is 50.8 mm.
CN202010947318.6A 2020-09-10 2020-09-10 Few-period high-field-intensity coherent THz radiation source generation system Pending CN112152048A (en)

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